Couch Grass (Elymus repens), also widely called quackgrass, is a perennial rhizomatous grass in the Poaceae family. Native to Europe, Asia, and North Africa and now widespread elsewhere, it produces long creeping underground rhizomes that allow it to spread aggressively. The rhizome is the plant part traditionally used.
In older herbal traditions, the rhizome of couch grass was prepared in decoctions and other simple household remedies. It is one of several common field plants that moved from weed status into traditional herbal use.
Because of its vigorous underground spread, couch grass is more often discussed as a persistent garden problem than as a cultivated herb.

